A Sumatran tiger kept at London zoo has been killed by its potential mate during their first meeting. Keepers had hoped the big cats would breed but have been left devastated after Asim, the male they brought in, attacked Melati.

The Zoological Society of London (ZSL) kept the two tigers in adjacent enclosures for 10 days to allow them to become accustomed to each other. After their keepers saw positive signs, they decided to make the “high-risk” introduction on Friday morning.

“Their introduction began as predicted but quickly escalated into a more aggressive interaction. Zoo staff immediately implemented their prepared response, using loud noises, flares and alarms to try and distract the pair, but Asim had already overpowered Melati,” the ZSL said.

“Zookeepers were eventually able to secure Asim in a separate paddock so that they could safely get to Melati where our vets confirmed that she had sadly died. Everyone at ZSL London Zoo is devastated by the loss of Melati, and we are heartbroken by this turn of events.”

The 10-year-old female had had three litters with her former mate, Jae Jae, and an image of her playing with one of her cubs was featured among the Guardian’s photos of the day in September 2016. The ZSL said five of her cubs survived to adulthood and have since been rehoused across Europe.

Asim, who is seven years old, was brought in from Denmark on 29 January, with Jae Jae heading to a French park. Keepers had assessed Asim as a “confident cat who is known for being very affectionate with the ladies”. He was matched with Melati through a Europe-wide breeding programme that aims to save the species from extinction and keepers in London had high hopes the plan would work.

Early signs were encouraging. “There has been lots of ‘chuffing’, which is a happy sound they make to let each other know they have good intentions,” they said shortly after Asim’s arrival in London. “It’s fantastic to see that they’re interested in each other already.”

But they cautioned meetings between big cats, however carefully planned, are “always considered to be high risk”. ZSL said its Tiger Territory attraction would remain closed for the rest of Friday while its team focused on caring for Asim.